MIUtilVariant.h

//===-- MIUtilVariant.h -----------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#pragma once

// In-house headers:
#include "MIDataTypes.h"

//++ ============================================================================
// Details: MI common code utility class. The class implements behaviour of a
//          variant object which holds any data object of type T. A copy of the
//          data object specified is made and stored in *this wrapper. When the
//          *this object is destroyed the data object hold within calls its
//          destructor should it have one.
//--
class CMIUtilVariant
{
    // Methods:
  public:
    /* ctor */ CMIUtilVariant();
    /* ctor */ CMIUtilVariant(const CMIUtilVariant &vrOther);
    /* ctor */ CMIUtilVariant(CMIUtilVariant &vrOther);
    /* ctor */ CMIUtilVariant(CMIUtilVariant &&vrwOther);
    /* dtor */ ~CMIUtilVariant();

    template <typename T> void Set(const T &vArg);
    template <typename T> T *Get() const;

    CMIUtilVariant &operator=(const CMIUtilVariant &vrOther);
    CMIUtilVariant &operator=(CMIUtilVariant &&vrwOther);

    // Classes:
  private:
    //++ ----------------------------------------------------------------------
    // Details: Base class wrapper to hold the variant's data object when
    //          assigned to it by the Set() function. Do not use the CDataObjectBase
    //          to create objects, use only CDataObjectBase derived objects,
    //          see CDataObject() class.
    //--
    class CDataObjectBase
    {
        // Methods:
      public:
        /* ctor */ CDataObjectBase();
        /* ctor */ CDataObjectBase(const CDataObjectBase &vrOther);
        /* ctor */ CDataObjectBase(CDataObjectBase &vrOther);
        /* ctor */ CDataObjectBase(CDataObjectBase &&vrwOther);
        //
        CDataObjectBase &operator=(const CDataObjectBase &vrOther);
        CDataObjectBase &operator=(CDataObjectBase &&vrwOther);

        // Overrideable:
      public:
        virtual ~CDataObjectBase();
        virtual CDataObjectBase *CreateCopyOfSelf();
        virtual bool GetIsDerivedClass() const;

        // Overrideable:
      protected:
        virtual void Copy(const CDataObjectBase &vrOther);
        virtual void Destroy();
    };

    //++ ----------------------------------------------------------------------
    // Details: Derived from CDataObjectBase, this class is the wrapper for the
    //          data object as it has an aggregate of type T which is a copy
    //          of the data object assigned to the variant object.
    //--
    template <typename T> class CDataObject : public CDataObjectBase
    {
        // Methods:
      public:
        /* ctor */ CDataObject();
        /* ctor */ CDataObject(const T &vArg);
        /* ctor */ CDataObject(const CDataObject &vrOther);
        /* ctor */ CDataObject(CDataObject &vrOther);
        /* ctor */ CDataObject(CDataObject &&vrwOther);
        //
        CDataObject &operator=(const CDataObject &vrOther);
        CDataObject &operator=(CDataObject &&vrwOther);
        //
        T &GetDataObject();

        // Overridden:
      public:
        // From CDataObjectBase
        ~CDataObject() override;
        CDataObjectBase *CreateCopyOfSelf() override;
        bool GetIsDerivedClass() const override;

        // Overrideable:
      private:
        virtual void Duplicate(const CDataObject &vrOther);

        // Overridden:
      private:
        // From CDataObjectBase
        void Destroy() override;

        // Attributes:
      private:
        T m_dataObj;
    };

    // Methods
  private:
    void Destroy();
    void Copy(const CMIUtilVariant &vrOther);

    // Attributes:
  private:
    CDataObjectBase *m_pDataObject;
};

//---------------------------------------------------------------------------------------
//---------------------------------------------------------------------------------------
//---------------------------------------------------------------------------------------

//++ ------------------------------------------------------------------------------------
// Details: CDataObject constructor.
// Type:    Method.
// Args:    T   - The object's type.
// Return:  None.
// Throws:  None.
//--
template <typename T> CMIUtilVariant::CDataObject<T>::CDataObject()
{
}

//++ ------------------------------------------------------------------------------------
// Details: CDataObject constructor.
// Type:    Method.
// Args:    T       - The object's type.
//          vArg    - (R) The data object to be stored in the variant object.
// Return:  None.
// Throws:  None.
//--
template <typename T> CMIUtilVariant::CDataObject<T>::CDataObject(const T &vArg)
{
    m_dataObj = vArg;
}

//++ ------------------------------------------------------------------------------------
// Details: CDataObject destructor.
// Type:    Overridden.
// Args:    T   - The object's type.
// Return:  None.
// Throws:  None.
//--
template <typename T> CMIUtilVariant::CDataObject<T>::~CDataObject()
{
    Destroy();
}

//++ ------------------------------------------------------------------------------------
// Details: Retrieve the data object hold by *this object wrapper.
// Type:    Method.
// Args:    T   - The object's type.
// Return:  T & - Reference to the data object.
// Throws:  None.
//--
template <typename T>
T &
CMIUtilVariant::CDataObject<T>::GetDataObject()
{
    return m_dataObj;
}

//++ ------------------------------------------------------------------------------------
// Details: Create a new copy of *this class.
// Type:    Overridden.
// Args:    T   - The object's type.
// Return:  CDataObjectBase *   - Pointer to a new object.
// Throws:  None.
//--
template <typename T>
CMIUtilVariant::CDataObjectBase *
CMIUtilVariant::CDataObject<T>::CreateCopyOfSelf()
{
    CDataObject *pCopy = new CDataObject<T>(m_dataObj);

    return pCopy;
}

//++ ------------------------------------------------------------------------------------
// Details: Determine if *this object is a derived from CDataObjectBase.
// Type:    Overridden.
// Args:    T   - The object's type.
// Return:  bool    - True = *this is derived from CDataObjectBase
//                  - False = *this is an instance of the base class.
// Throws:  None.
//--
template <typename T>
bool
CMIUtilVariant::CDataObject<T>::GetIsDerivedClass() const
{
    return true;
}

//++ ------------------------------------------------------------------------------------
// Details: Perform a bitwise copy of *this object.
// Type:    Overrideable.
// Args:    T       - The object's type.
//          vrOther - (R) The other object.
// Return:  None.
// Throws:  None.
//--
template <typename T>
void
CMIUtilVariant::CDataObject<T>::Duplicate(const CDataObject &vrOther)
{
    CDataObjectBase::Copy(vrOther);
    m_dataObj = vrOther.m_dataObj;
}

//++ ------------------------------------------------------------------------------------
// Details: Release any resources used by *this object.
// Type:    Overridden.
// Args:    None.
// Return:  None.
// Throws:  None.
//--
template <typename T>
void
CMIUtilVariant::CDataObject<T>::Destroy()
{
    CDataObjectBase::Destroy();
}

//---------------------------------------------------------------------------------------
//---------------------------------------------------------------------------------------
//---------------------------------------------------------------------------------------

//++ ------------------------------------------------------------------------------------
// Details: Assign to the variant an object of a specified type.
// Type:    Template method.
// Args:    T       - The object's type.
//          vArg    - (R) The object to store.
// Return:  None.
// Throws:  None.
//--
template <typename T>
void
CMIUtilVariant::Set(const T &vArg)
{
    m_pDataObject = new CDataObject<T>(vArg);
}

//++ ------------------------------------------------------------------------------------
// Details: Retrieve the data object from *this variant.
// Type:    Template method.
// Args:    T   - The object's type.
// Return:  T * - Pointer the data object, NULL = data object not assigned to *this variant.
// Throws:  None.
//--
template <typename T>
T *
CMIUtilVariant::Get() const
{
    if ((m_pDataObject != nullptr) && m_pDataObject->GetIsDerivedClass())
    {
        CDataObject<T> *pDataObj = static_cast<CDataObject<T> *>(m_pDataObject);
        return &pDataObj->GetDataObject();
    }

    // Do not use a CDataObjectBase object, use only CDataObjectBase derived objects
    return nullptr;
}